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68108021 = 531285057
BaseRepresentation
bin1000000111100…
…11111011110101
311202011020122022
410003303323311
5114413424041
610431442525
71454623442
oct403637365
9152136568
1068108021
1135499623
121a986445
1311158607
14908c9c9
155ea524b
hex40f3ef5

68108021 has 4 divisors (see below), whose sum is σ = 69393132. Its totient is φ = 66822912.

The previous prime is 68108017. The next prime is 68108059. The reversal of 68108021 is 12080186.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 54967396 + 13140625 = 7414^2 + 3625^2 .

It is a cyclic number.

It is not a de Polignac number, because 68108021 - 22 = 68108017 is a prime.

It is a super-4 number, since 4×681080214 (a number of 32 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68108071) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 642476 + ... + 642581.

It is an arithmetic number, because the mean of its divisors is an integer number (17348283).

Almost surely, 268108021 is an apocalyptic number.

It is an amenable number.

68108021 is a deficient number, since it is larger than the sum of its proper divisors (1285111).

68108021 is a wasteful number, since it uses less digits than its factorization.

68108021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1285110.

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 68108021 is about 8252.7583873515. The cubic root of 68108021 is about 408.3815254889.

The spelling of 68108021 in words is "sixty-eight million, one hundred eight thousand, twenty-one".

Divisors: 1 53 1285057 68108021